Inflatable helmet



FIG. 1 is a front, right side perspective view of an inflatable helmet showing my new design, the detail shown in broken lines is for illustrative purposes only and forms no part of the claimed design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a rear elevational view thereof; and,

FIG. 6 is a bottom plan view thereof. 

I claim the ornamental design for an inflatable helmet, as shown and described. 